Wednesday, June 18, 2008

Glenfinnan Monument at Loch Shiel

This is a shot of the Jacobite memorial at Glenfinnan, Scotland on the shore of Loch Shiel. This spot is marked in history as the place the final Jacobite rebellion started from, after the defiant raising of the Royal Standard on August 19th 1745. Prince Charlie managed to inspire the confidence and support of the loyal clansmen and it was here they rallied in support of the Stewart monarchy.

I've posted this as another example of what HDR can do to allow us to render a scene with way too much dynamic range (too wide a range from the darkest to the lightest parts of the scene). HDR lets us combine a bracketed set of exposures into one image that more closely matches what our eyes can see but cameras just can't record.

I've read that our eyes can see a range of about 23 f/stops or exposure values while a camera can record only 6 to 7. The pupils of our eyes adjust to the light level as we gaze across a scene and we see the detail in the shadows and in the highlights. The camera sensor just can't adjust the way it records the scene from pixel to pixel but must pick an average value for the entire sensor to use. HDR processing takes a range of exposures and combines them to allow a wider range of values to be captured. For instance, to record the hills, the sky and clouds would be blown out or to record the clouds properly, the hills and trees would be almost black. HDR takes the best exposed parts of the images and uses them to construct one final image that matches what we see.

5-exposure (2/3 ev step) HDR via Photomatix Pro

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